Gambling and substance use disorders are highly comorbid conditions. While pathological gambling affects only about 1% of the population, the sub-diagnostic threshold condition, problem gambling, is present in about 4% of the general population and up to 10-20% of substance abusers. Despite high rates of comorbidity and adverse consequences associated with problem gambling, few substance abuse treatment programs screen for gambling problems and even fewer provide gambling-specific treatment services. This project will evaluate the efficacy of two brief interventions for individuals seeking treatment for substance use disorders who also have gambling problems. In total, 220 problem gambling substance abusers will be randomized to one of three conditions: (1) a control condition consisting of 10 minutes of psychoeducation about gambling, (2) 10 minutes of brief advice about problem gambling and how to reduce it, or (3) four sessions of motivational and cognitive-behavioral therapy. The brief advice provides behavioral norms as well as prescriptive information about how to reduce gambling. The four-session intervention is designed to bolster motivation to change one's gambling behavior and also provides skills training in identifying high-risk situations for gambling and practicing alternative responses to them. All participants will receive standard substance abuse treatment at their respective clinics, and assessments will occur before the gambling intervention, and 2, 5, 8, 12, 16, 20 and 24 months later. Instruments measuring gambling behaviors and problems, substance use, psychosocial functioning, and HIV risk behaviors will be administered. Collaterals will be interviewed to provide independent perspectives on participants' gambling involvement. Results from this study will provide important information regarding the efficacy of brief interventions for reducing gambling and related problems in substance abusers.